1. Field of the Invention
Embodiments of the present invention relate to a light emitting device package and a lighting system.
2. Discussion of the Related Art
A light emitting device (LED) includes a p-n junction diode, whose characteristic includes converting electric energy into light energy and which is manufactured by, for example, combining Group III and Group V elements in the periodic table into a compound semiconductor. The LED may be made to display a variety of colors by adjusting the composition ratio of the compound semiconductor.
The LED emits energy that corresponds to an energy gap between a conduction band and a valance band, which occurs after electrons of an n-layer and holes of a p-layer are combined during applying of forward voltage. This energy is typically emitted in a form of heat or light, and is emitted in the form of light in the LED.
For example, since a nitride semiconductor has a high thermal stability and wide band-gap energy, it receives a lot of attentions from optical device and high-output electronic device development fields. Especially, a blue LED, a green LED, and an UV LED, which use a nitride semiconductor, are commercialized and extensively used.
A related art white LED module is realized by combining separate R, G, and B light sources or by combining a blue or ultraviolet light source and a fluorescent material.
In relation to a typical fluorescent material converting method that applies yellow fluorescent material on the edge of a blue LED, light converted from the yellow fluorescent material is emitted, such that it is emitted to all directions. Then, the light re-entering the inside of a light emitting device is absorbed into the device while inside, thereby causing optical loss of the re-entered light, such that light emitting efficiency of the light emitting device is deteriorated.